There is a temperature sensor 9 which, as illustrated in FIG. 30, includes a temperature sensitive device 2, a sheath pin 3 in which a pair of signal lines 31 leading to the temperature sensitive device 2 are disposed, a metal cover 4 fit on the top to cover the temperature sensitive device 2, and a rib 6 retaining the outer periphery of the sheath pin 3 (Patent Document 1). In the temperature sensor 9, the sheath pin 3 and the rib 6 are welded together.
In the case where the temperature sensor 9 is, as illustrated in FIG. 31, mounted in the exhaust system of an internal combustion engine, a temperature sensitive portion 96 in which the temperature sensitive device 2 is disposed is inserted into the exhaust pipe 80. The rib 6 is placed in contacting abutment with a top surface 811 of a boss 81 provided on the exhaust pipe 80.
The internal combustion engine in which the temperature sensor 9 is mounted in the above manner vibrates during running, so that vibrations are transmitted from the exhaust pipe 80 to the boss 81, to the rib 6, and to the sheath pin 9 of the temperature sensor 9. The rib 6 and the sheath pin 3 is welded together, so that the vibrations are transmitted from the rib 6 directly to the sheath pin 3.
The vibrations of the sheath pin 3 will, therefore, be strong vibrations (high frequency and amplitude), which may cause the temperature sensitive portion 96 to vibrate at a high acceleration level.
As a result, an excessive degree of stress may be exerted on the top end portion of the sheath pin 3, the temperature sensitive device 2 provided on the top end portion, or the joint between the sheath pin 3 and the rib 6.
The exertion of the stress on the temperature sensitive device 2 may result in breakage thereof or disconnection of the electrode 21 of the temperature sensitive device 2.
The excessive exertion of the stress on the joint between the sheath pin 3 and the rib 6 may result in cracks in or breakage of the weld or the sheath pin 3.
There is disclosed a structure in which a guard member is disposed on the outer periphery of the sheath pin, and a damper made of an elastic material is interposed between the guard member and the sheath pin in order to dampen the vibrations of the sheath pin (Patent Document 2).
Patent Document 3 discloses the structure in which a capsule portion is provided on the outer periphery of the sheath pin. The capsule portion is, however, fixed to the outer periphery of the sheath pin through clamping.    Patent Document 1: Patent Publication No. 2000-162051    Patent Document 2: U.S. Pat. No. 4,525,081    Patent Document 3: U.S. Pat. No. 3,826,098